


An Unexpected Turn

by LadyDarkPhoenix (Phoenixfire)



Series: Tumblr Prompt Fills [1]
Category: Captain America (Movies)
Genre: BDSM, Bisexual Steve Rogers, Dom Steve Rogers, Dom/sub, F/M, Polyamory
Language: English
Status: Completed
Published: 2018-12-10
Updated: 2018-12-10
Packaged: 2019-09-15 10:32:29
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,004
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16931634
Author URL: https://archiveofourown.org/users/Phoenixfire/pseuds/LadyDarkPhoenix
Summary: An innocent date night with Tony's girl to get to know each other if they're going to make the Polyamorus relationship they've found themselves in work takes an unexpected turn for Steve when Cosima makes a startling admission that changes the relationship between the two of them.





	An Unexpected Turn

**Author's Note:**

> J: *pretends to innocently whistle while dropping off two prompts* “Lie back and let me take care of you.”...“Foreplay isn’t optional. It’s required.”
> 
> Tumblr prompt fill based off the Lost and Found universe because they didn't specify a ship and I've had this head cannon about these two for a while now.

Cosima laughed as Steve carried her into the tower after an evening out just the two of them, Bucky and Tony left home to themselves until the next morning. It was nice spending time with the artistic soldier, it didn't happen that often and Cosima was surprised they got on so well. When he'd suggested them spending the night together she immediately agreed.

He took her to his floor and placed her on the couch, capturing her lips in a savage kiss before growling, “I've been wanting to do that all night.”

“Yeah? Is that all you have wanted to do?” Cosima started pulling his shirt out of his pants as she nipped at his throat.

“Cosima, what?”

“I may have had a change of mind, if you want the challenge of taking me,” she unbuttoned his shirt as she spoke.

Steve was speechless for a moment as he watched her, he never thought the woman would ever offer herself to him, she was so adamant about only wanting Tony sexually, he figured this would only be an unfulfilled fantasy. “Y-yes, God I've wanted you for so long.”

“So let us enjoy our evening,” she pushed his shirt back, trying to get it off, “I want you so much Steven.” 

Steve used one hand to stroke her cheek, down her neck, stopping at the swell of her cleavage as Cosima pressed into his touch. “You want me huh?” Removing his hand, he took off the button down and pulled off his undershirt before sitting on the opposite end of the couch. He undid his belt buckle and pants button before unzipping his fly, “get over here, foreplay isn't optional. It's required.”

“Are we using colors and taps?” She asked, sliding to her knees before positioning herself before him, hands on his legs.

“Of course, I have a feeling this isn't going to be gentle for either of us.” He freed his half hard cock from the confines of his underwear, chuckling a little at her appreciative moan before grabbing her hair to lead her mouth where he wanted. 

Cosima gasped at the sudden, rough handling, but eagerly wrapped her lips around the head, teasing the slit with her tongue as she sucked. He watched her as she moved down, taking more of him before wrapping one hand around the base. Steve groaned as she started working him, hand sliding with the rhythm of her head as it bobbed.

Steve let her go for a bit, petting her head, enjoying the sight of the strong woman pleasuring him, but it wasn't quite what he wanted. He grabbed the blonde hair again with one hand while the other pulled her hand off of him before pushing her further down his impressive length, groaning as he pressed into her throat making her gag but she didn't tap out. He proceeded to use his hold on her to make her keep taking him deep, making sure to let her up for sufficient air, but loving the sounds she was making as her throat spasmed around him until finally he let himself go, “swallow it all like a good girl.”

Cosima obliged, suckling at him long after he'd finished until he felt himself start to swell again. She finally pulled off him with an obscene pop before using her now rough voice to ask, “was that good for you?”

He looked down at her, pupils blown, “God Cos, you're amazing.” She stood and bent down so he could kiss her lips, tasting himself as she nipped at him. Cosima let out a little shriek as Steve was on her, ripping her shirt and undoing the front clasp of her bra before kissing her neck before one hand started fondling her. She let out a high pitched whine as his thumb circled a nipple while he sucked a mark onto her.

“Steven,” she breathed as he moved his head to cover her neglected side with his mouth, lapping at the sensitive skin as he sucked. Steve kept her distracted as his free hand moved under her skirt to start slowly stroking her through already damp panties, chuckling as her hips started moving. Cosima tried to move away, but was trapped as he easily lifted her, her arms going to his shoulders and legs going around his waist so she wouldn't fall.

“Now, now,” Steve chided as he felt himself slide against her covered slit, “who said I was done?” He easily held her in one arm as he reached down, taking himself in hand before using a finger to move her underwear out of the way as he lined himself up.

Cosima cried out as he started entering her tight chanel, body used to the thinner girth of Tony compared to the wide, long member that graced Steve's body. As he pulled her flush against him, she bent forward, biting into his neck to distract herself from the temporary pain, making him hiss before lifting her up for a bit of friction.

“Oh God,” she moaned as he moved her, using her body to chase his own pleasure.

“Is it wrong I want to see how many times I can get you to come before I have you begging me to stop?” 

“I am young,” Cosima panted as she moved her hips, “are you sure an old man like you can keep up?”

“Think I'm up for the challenge,” he smirked as he carried her to the bedroom, enjoying the way she whined impaled upon him but never loosened her legs to free herself. When Steve got them into the room, he pressed Cosima's back against the door to close it before moving his hands to her hips so he could move her more easily on him. He couldn't help but watch her face as he used her to come again. The gasps and whines as he studied her blissful face put a smile on his. As much as he loved his boys, there was something about pleasing a woman that was unique.

As he finished yet again, Steve carried Cosima to the bed, tossing her down before straddling her. Using one hand, he started stroking her wet slit.

“I gave you something, time to repay the favor,” Cosima's voice came breathlessly as she continued to undulate under him, “get comfortable. I do not want to lose anymore clothes.”

Obeying, Steve moved off her to quickly remove what little clothing he had left as she shed hers, tossing them away before moving to the end of the bed.

“Show me how well you can use that mouth Captain,” Cosima ordered as she spread her legs wide for him.

Steve smiled, a devilish glint in his eyes as he positioned himself between her legs. He started kissing up one thigh then the other before biting down, sucking another mark into her pale skin and enjoying the slightly pained whine he received in response before nails dug into his scalp to urge him on. He kissed the purpling flesh before focusing on the task at hand. Wrapping his arms around her thighs to trap her as wide as she would go, Steve finally gave her leaking slit a slow lick, getting as much of the mixture of them as he could. 

He proved most talented at the task. Steve found that Cosima twitched in ecstasy when he worked her clitoris just so with his teeth and took full advantage of that knowledge to turn her into a quivering mess as his strong grip kept her trapped at his mercy.

“S-Steven, p-please,” Cosima cried as he wrenched climax after climax from her with his mouth.

Pulling away, Steve smiled up at her tear stained face, “please what gorgeous?”

“Please take me again.”

“How would you like me to do that?”

Cosima blushed, not used to being the one begging for what she wanted. She was adept at domination but to submit like this was completely new to her. She could see how the submissives she worked with found it appealing with the right person and Steven was definitely the right person for her.

“However you want me,” she hesitated a moment before adding, “sir…”

Steve blinked in surprise before moving to cover her body with his, “sir? Are you sure?”

Nodding, Cosima pulled him down for a desperate kiss before replying, “cannot promise to be a good little sub but if you can tame me occasionally I would not mind.”

“Cosima,” he breathed her name reverently. Never in his wildest dreams did he think that this fierce, strong woman would want to submit to him. It was a gift Steve wasn't going to take lightly.

“We can discuss terms later but for now, claim me please,” she begged, “make me yours.”

He stroked her gently, fingers tracing over the stars on her ribs as he thought over how to proceed now that their dynamic had changed. Making up his mind, Steve kissed her again, before pulling her legs over his shoulders, “I want to watch you. You're beautiful when you lose yourself in the moment.”

Entering her slowly this time, Steve wanted this time to last for both of them. Cosima whimpered at the change of pace, oversensitive after everything else he'd done, arching her back as he filled her. Her eyes fluttered closed as he set a maddeningly slow pace, her hands straying to tease her nipples for some form of stimulation to help the building pleasure inside her. A disappointed moan escaped her as he adjusted to trap her wrists to the bed with his hands, folding her almost in half as he pressed deeper inside.

“Ah, ah, ah,” Steve chided, “you get what I give you or I'll leave you frustrated. You may beg if you need to but I won't promise anything. Let me hear you beg gorgeous.”

The struggle written across her face as he continued the slow, pleasurous torture between them was worth ignoring his own desire to quicken his pace as Steve saw the moment Cosima truly surrendered her mind to the role she had asked him for.

“Please sir, I need more.” Cosima's now broken sounding voice finally spoke as more tears fell, her hips uselessly trying to urge him on. “God please, please, please, sir. Faster, harder, use me sir, please. Please sir, please!”

Steve let her beg for a few more moments before he couldn't contain himself anymore, his blood boiling with everything that had transpired and he didn't want to hold back any longer now that she'd finally broken completely. Snapping his hips hard against her, he bent down to cover her mouth with his own. Cosima's body jolted roughly with every violent thrust as her cries were smothered. 

Steve stopped the kiss as he got closer as he felt her coming around him, Cosima couldn't help from crying out as the overwhelming sensitivity started bordering on pain as he continued to use her, overstimulated body.

“Sir, stop it hurts. Oh God, God please it's too much!”

The feeling of her multiple orgasms on top of getting her to admit he'd fucked her raw pushed Steve over the edge one last time. As he felt the familiar tightening of his release, he pulled out to send the white streams of come over her body, marking her as his.

“Thank you sir,” Cosima panted, running her fingers through the mess on her body, licking his essence off them lazily.

Steve admired the scene in front of him, at the utterly wrecked woman that had come apart at his hands. As much as it made him want to continue, he knew it was time to take care of her and end the night before any damage could be done.

“Will you be okay for a moment while I go get something to clean us up?”

“Bath,” Cosima asked quietly as she tried to focus on him but wasn't quite successful.

“Sure, stay right there and I'll be back for you,” he retrieved a blanket, a bottle of water, and a small bag of nuts before he left her. “I'm going to leave these with you,” Steve set the water and snack on the table before pulling her gently into his arms to wrap her in the blanket and kissing the top of her head, “I won't be long.”

Pulling the warm fabric tightly around her, Cosima nodded, cracking open the water as she watched him go. She hoped he didn't notice the slight tremble in her hands from the fear of being left alone after what she'd been through. It made sense to her logical mind what was happening, she'd provided enough after care in her time to know what was going on and that Steve would return for her but that didn't stop her mind from wondering if the contrary were true. She found her thoughts racing to what she'd done wrong to upset him enough to make him leave her so soon afterwards even as she tried to make them stop. Wondered what was wrong with her for allowing him to dominate her, wondered if she was weak for wanting him to.

When Steve returned not long after he'd left, he found Cosima curled up in a ball shivering uncontrollably with tears running down her face. “Cosima, what's wrong?” He rushed over to her, recognizing the signs of a drop.

“I… what…” she struggled to form words as he gathered her up, carrying her into the bathroom.

“Shh, you were perfect my darling girl,” he reassured her, “so sweet and good. For your first time, you did so well. I'm so happy with how you did. Now let me take care of you, give you everything you need my good little girl.”

Nestling closer into him, Cosima quieted a bit as he kept up his praise. She didn't know she needed to hear what he was saying until Steve started. He gently unwrapped her from the warm cocoon of the blanket before slipping her into the steaming water, joining her.

“Sorry,” she whispered, body relaxing as the combination of warmth and Steve's hands massaging her shoulders worked magic on frayed nerves, “I have never…”

“It's alright,” Steve pulled her back to rest against his chest, “I shouldn't have left you so quickly. Haven't been with a new sub since Tony but you and Buck helped me navigate that. Haven't been someone's first dom since Bucky way back. Guess I forgot how easy it is for someone to fall apart. Might have also make a mistake in thinking you wouldn't because of who you are, I'm sorry for that.”

“Who I am,” she blinked up at him in wonder, “what do you mean?”

Steve held her tight as he spoke, “you're such a strong woman able to keep Tony and everyone else in line and well taken care of I made the mistake of thinking you'd be the same way as a sub. Didn't realize that you'd be a beautiful, delicate flower after being taken apart. Nothing wrong with that but you know as well as I do that I should have been more attentive to your needs, I failed you in that and for that I truly am sorry.”

“You are making up for it now Steven,” Cosima pointed out, “that is what matters most.

Angling her head, Steve gently lifted her chin up to give her a kiss, loving the sweet little whine from her at the gesture, “thank you for trusting me Cosima. This is a great gift you've given me, I'll treasure it for as long as you offer yourself to me.”

“You really think I was good for you,” she sounded uncertain of herself. Not her usual, confident demeanor in the way she seemed to shrink from him.

“I'll keep telling you how perfect you were until you believe it my sweet girl, my Cosima. Now let me clean you up so we can relax in bed with a snack and maybe a movie. I won't let you go again, promise.”

Letting Steve take care of her felt nice. Cosima noticeably calmed as he washed them both of the sticky mess they'd made, surprising herself that she didn't mind the small liberties he took when handling her body. His hand lingering on her breast as he rinsed off soap or the way his finger slipped inside her sore folds as he made sure everything was clean. It actually made her feel cared for that he still wanted to touch her in those places after making a fool of herself earlier. 

It was almost disappointing when he deemed them both clean, getting out to get towels for them; drying himself off and wrapping the fabric around his waist before gathering her up in another. Cosima quietly let him carry her back to the bedroom to watch as he collected pajamas for them both, feeling small as he put her in oversized fleece pants and a long sleeved t-shirt before stripping the bed of soiled sheets and making it anew.

“Doing alright there darling?” Steve looked over to her sitting in silence as he put a fresh warm blanket on the bed.

“I was good?”

“Perfect,” he smiled warmly, “let's get some food for us and I'll keep telling you until you believe it.”

Carrying her with him to the kitchen, Steve made a few sandwiches and grabbed a few other things to make a light meal for them as Cosima sat again watching him work. Situating everything in her arms when he finished, he carried her and everything she held back to the bedroom before organizing their things on the table.

“Just lie back and let me take care of you,” he told her, organizing a few pillows so he could sit up against the headboard. Cosima complied, moving closer so she could put her head on his lap before tugging his arm around her. “So you need physical contact after,” Steve commented as he ran his fingers through her hair, “good to know. Want me to hand feed you?”

“Yes please.”

“Anything you want to watch while we eat?”

“Maybe a Romero movie,” she cautiously replied.

“Don't think I've seen anything with them.”

“He directed the classic original zombie movies…” Cosima went on to extol the wonders of the movies with a passion. He let her go for a while before placing a finger on her lips to quiet her.

“Alright little girl, we'll watch your movie if you promise to settle down and let me feed you.”

She shifted to look up at him, “yes sir.”

Having J.A.R.V.I.S. start the movie, Steve leisurely broke up small bites of food for Cosima before giving them to her. He was surprised at the movie choice after a few scenes, but she seemed content nibbling bites from his fingers as the gory scenes played out. It was sweet how she snuggled against him, preening a little at his gently murmured praises. 

After the movie was over and Cosima was more relaxed and coherent, Steve pulled her up to sit next to him. “We need to talk about what happened. Why you dropped and how we proceed from here.”

“Thought we had already covered that,” Cosima bit her lip as she looked at him.

“One more time for me so I can understand.”

Sighing, she tried to look away but he caught her chin in his hand to make her look at him. Cosima struggled with herself before giving in. “I do not know exactly what happened. I knew you were not leaving me for long but my mind kept jumping to a conclusion that because I gave in and let you dominate me that you were disgusted at my actions. That you thought of me as less because I presented myself as a strong dominatrix for so long. Steven there are times where I crave someone to take control, to make me submit, make me feel the love and care I show to my own submissives. I need someone that is capable of making me take what I want with the understanding that I may fight back, will never be the passive kind of submissive that Anthony is, will never be what most consider good, but is willing to work with me on a balance that suits everyone involved. I have not been able to find that person yet, maybe I never will. But I did like what we did tonight, it was the closest I have had to getting what I desire but I understand if you do not want me in that way.”

“Why wouldn't I want you?” His eyebrows furrowed in confusion, “was there something I did aside from leaving you too soon to give you the idea that I didn't enjoy every moment of our activities tonight? Because you were amazing Cos, simply perfect. If I didn't like your fighting, your violent struggle against what I was doing I could have easily stopped you. If you had said the word, I would have stopped trying to control our activities and let you lead but that's obviously not what you wanted. If you're asking me to give you what you want when you want it,” Steve wiped the single tear that had escaped her eye as he spoke, “well, it wouldn't be the worst thing for us considering it seems we're already stuck in a relationship with each other because of our men. I'm sure they'd be happy to know we've got something between us.”

“You want something between us,” surprise colored her voice as she looked into his eyes.

Steve chuckled, “isn't there already? You and I have become close with everything that's happened, at least I'd like to think so. If you think I can give you what you need, I'd be more than willing to figure out how to do it if that's what you want. But only if that's what my little girl wants.”

“I like that,” Cosima whispered with a blush.

“Like what?”

“You calling me little girl,” she admitted, “the way you make me feel so tiny when you hold me. The way you can overpower me but so gentle when you did. I think…”

“Cos?” Steve waited with bated breath for her to continue.

“I think I can see where Anthony and Mia come from now. Steven can we do this, can we somehow be together all of us?”

“If you can get along with Buck than I don't see why we can't,” he ran his fingers through her hair, “can you do that little girl?”

Cosima's eyes slid closed as he petted, “I do not hate him. The way Anthony acts towards him compared to me is why I avoid him, I am jealous he seems to mean more to him than I do at times.”

“You need to talk to Tony about that, but if you can accept Bucky then I'd be willing to give us a shot.”

“I will, I can,” she promised.

Steve smiled at her, “than it's official. You're my little girl.”

“Thank you sir,” Cosima blushed slightly, “I hope I will not disappoint you.”

“Let's sleep now. You haven't disappointed me, I don't think you're weak for asking for something you need and I just hope I'm worthy enough of the precious gift you've offered me.”

“Thank you Steven,” she whispered before moving closer so she could brush a kiss to his lips. He maneuvered them so he was laying on his back, Cosima tucked under his arm with her head on his chest. She loved feeling so small but protected as Steve had the lights turned off. 

Maybe their unusual multi-person relationship could work out, maybe the four of them could be happy together, maybe she could love more than one man, Cosima thought as sleep overcame her, maybe it just took the right people to come together at the right time to make her realize the truth.


End file.
